APPLICATION OF A SIMPLE AND EFFICIENT SOURCE EXCITATION TECHNIQUE TO THE FDTD ANALYSIS OF WAVE-GUIDE AND MICROSTRIP CIRCUITS

A simple, efficient, and unified source excitation scheme for the fini te-difference time-domain (FDTD) analysis of both waveguides and micro strip circuits is developed and validated, In this scheme, by moving t he source plane several cells inside the terminal plane and adding the excitation wave as an extra term in the FDTD equation, the interactio n between the excitation and reflected waves are totally separated in time domain, Hence, for both waveguide and microstrip discontinuities, absorbing boundary conditions can be applied on the terminal plane di rectly, In particular, for microstrip circuits, our scheme does not in duce any source distortions when a simplified field distribution is us ed as the excitation, Consequently, the terminal plane can be moved ve ry close to the discontinuity and thus significant computational savin gs are achieved. In addition, for microstrip systems, the validity and efficiency of the Mel's simplified field distribution are evaluated a nd confirmed for the first time.